Dundalk fall to Zenit and Aritz Aduriz sets new scoring record on a busy matchday four of the Europa League.

Jose Mourinho says Manchester United deserved to lose to Fenerbahce in Europa LeagueReuters

Manchester United spurned the chance to take a big step towards qualification for the first knockout phase of the 2016/17 Europa League and now lie third in Group A after sinking to a disappointing 2-1 loss against Fenerbahce. Jose Mourinho's side, who inflicted a heavy defeat on the same opponents two weeks ago, were fighting an uphill battle almost from the outset after Senegalese striker Moussa Sow turned home Josef de Souza's early cross with a fantastic overhead kick from the edge of the penalty area.

United dominated possession after that costly start, but suffered another setback after 30 minutes when Paul Pogba visibly struggled to shake the impact of a heavy challenge and limped off with a suspected dead leg. Fenerbahce doubled their lead on the hour mark when substitute Zlatan Ibrahimovic, who was fortunate to avoid punishment for an ugly clash with Simon Kjaer, fouled Mehmet Topal and Sunderland loanee Jeremain Lens curled an impressive free-kick over the wall and past the stranded David de Gea.

Skipper Wayne Rooney reduced the deficit late on with a 30-yard piledriver that saw him equal Ruud van Nistelrooy as the club's leading European goalscorer, but the visitors were unable to find a late equaliser and saw a penalty shout turned down when Ander Herrera's hopeful shot appeared to strike the hand of former Liverpool stalwart Martin Skrtel.

A frustrated Mourinho can at least take solace from the fact that previous group leaders and next opponents Feyenoord were held to a 1-1 draw by Zorya Luhansk in Odessa. The Eredivisie outfit took the lead after 15 minutes when Nicolai Jorgensen headed home Dirk Kuyt's cross for his eighth goal in only nine games, but were denied all three points when Rafael Forster levelled with a penalty after Eric Botteghin had been dismissed for handball.

Moussa Sow netted an early goal to remember during Fenerbahce's 2-1 win over Manchester UnitedSTRINGER/AFP/Getty Images

While United toiled to no avail in Istanbul, Premier League rivals Southampton enjoyed arguably the greatest European night in their history with a home win over a badly underperforming Inter Milan team that sacked manager Frank de Boer this week after just 85 days in charge. Claude Puel's Saints initially fell behind to a Mauro Icardi strike and were left temporarily ruing their luck when penalty specialist Samir Handanovic saved a Dusan Tadic spot-kick following Ivan Perisic's handball and Antonio Candreva somehow got away with a yellow card for an elbow on Sam McQueen.

Virgil van Dijk was cruelly denied a penalty despite being clearly dragged down by Andrea Ranocchia at a set-piece, but shook off his frustrations to tuck away the rebound after Oriol Romeu was denied by the crossbar. Inter eventually sealed their own downfall when a cross from Tadic was put through his own net in almost comical fashion by the hesitant Yuto Nagatomo.

Zenit Saint Petersburg sealed their place in the next round with a 2-1 win over plucky Irish champions Dundalk at the Petrovsky Stadium. Brazilian midfielder Giuliano maintained their 100% record and improved his own tally to five with goals either side of an effort from winger Daryl Horgan. Group rivals Maccabi Tel Aviv and AZ Alkmaar played out a goalless draw in Israel.

Anderlecht thrashed Mainz 6-1 in Group C, but the individual performance of the night was unquestionably supplied by Aritz Aduriz. The veteran Spanish forward became the first player ever to score five goals in a single Europa League match in Athletic Bilbao's 5-3 win over Genk at San Mames. Three of those strikes came from the spot.

Aritz Aduriz scored all five of Athletic Bilbao's goals against GenkANDER GILLENEA/AFP/Getty Images

Villarreal suffered a shock rare home defeat at the hands of competition debutants Osmanlispor, while Schalke clinched top spot in Group I with a comfortable 2-0 win over Krasnodar. Shakhtar Donetsk and Ajax are also through after beating Gent and Celta Vigo respectively.